(function( global, factory ) {
    //For CommonJS and CommonJS-like
    if ( typeof module === "object" && typeof module.exports === "object" ) {
        module.exports = global.document ?
            factory( global, true ) :
            function( w ) {
                if ( !w.document ) {
                    throw new Error( "previewImage requires a window with a document" );
                }
                return factory( w );
            };
    } else {
        factory( global );
    }

// Pass this if window is not defined yet
}(typeof window !== "undefined" ? window : this, function(window){
    //解决遮罩层滚动穿透问题，分别在遮罩层弹出后和关闭前调用
    const ModalHelper = ( (bodyCls) =>{
        let scrollTop;
        return {
            afterOpen: function () {
                scrollTop = document.scrollingElement.scrollTop;
                document.body.classList.add(bodyCls);
                document.body.style.top = -scrollTop + 'px';
            },
            beforeClose: function () {
                document.body.classList.remove(bodyCls);
                document.scrollingElement.scrollTop = scrollTop;
            }
        };
    })('dialog-open');
    // display: none;

    var $ = {};
    var style = `#__previewImage-container
        {
            -ms-touch-action:none;
            touch-action:none;
            -webkit-touch-action:none;
            line-height:100vh;
            background-color:#000;
            width:10rem;
            height:100vh;
            position:fixed;
            overflow:hidden;
            top:0;
            left:0;
            z-index: 2147483647;
            font-weight:normal;
            transition:transform .3s;
            -ms-transition:transform .3s;
            -moz-transition:transform .3s;
            -webkit-transition:transform .3s;
            -o-transition:transform .3s;
            transform:translate3d(100%,0,0);
            -webkit-transform:translate3d(100%,0,0);
            -ms-transform:translate3d(100%,0,0);
            -o-transform:translate3d(100%,0,0);
            -moz-transform:translate3d(100%,0,0);
        }
        #__previewImage-container .previewImage-text{
            width:100%;
            height:0.6rem;
            line-height:0.6rem;
            position:absolute;
            bottom:1.6rem;
            text-align:center;
            color:#FFFFFF;
            z-index:10;
            letter-spacing: 5px;
        }
        #__previewImage-container .previewImage-box{
            width:100000rem;
            height:100vh;
        }
        #__previewImage-container .previewImage-box .previewImage-item{
            width:100vw;
            height:100vh;
            float:left;
            text-align:center;
            background:transparent;
        }
        #__previewImage-container .previewImage-box .previewImage-item.previewImage-nobackground{
            background:none;
        }
        #__previewImage-container .previewImage-box .previewImage-item .previewImage-image{
            vertical-align:middle;
            width:10rem;
        }`;

    $.isArray = function(value) {
      return Object.prototype.toString.call(value) == '[object Array]';
    }
    /**
     * get multiple elements
     * @public
     */
    $.all = function(selector, contextElement) {
      var nodeList,
        list = [];
      if (contextElement) {
        nodeList = contextElement.querySelectorAll(selector);
      } else {
        nodeList = document.querySelectorAll(selector);
      }
      if (nodeList && nodeList.length > 0) {
        list = Array.prototype.slice.call(nodeList);
      }
      return list;
    }

    /**
     * delegate an event to a parent element
     * @public
     * @param  array     $el        parent element
     * @param  string    eventType  name of the event
     * @param  string    selector   target's selector
     * @param  function  fn
     */
    $.delegate = function($el, eventType, selector, fn) {
      if (!$el) { return; }
      $el.addEventListener(eventType, function(e) {
        var targets = $.all(selector, $el);
        if (!targets) {
          return;
        }
        for (var i=0; i<targets.length; i++) {
          var $node = e.target;
          while ($node) {
            if ($node == targets[i]) {
              fn.call($node, e);
              break;
            }
            $node = $node.parentNode;
            if ($node == $el) {
              break;
            }
          }
        }
      }, false);
    };
    var _previewImage = function(){
        this.version = '1.0'; //版本号
        this.winw = window.innerWidth||document.body.clientWidth;  //窗口的宽度
        this.winh = window.innerHeight||document.body.clientHeight; //窗口的高度
        this.originWinw = this.winw;    //存储源窗口的宽度
        this.originWinh = this.winh;    //存储源窗口的高度
        this.marginRight = 0;  //图片之间的间隔->previewImage-item的margin-right
        this.imageChageMoveX = this.marginRight + this.winw;  //图片切换容器的x位移量
        this.imageChageNeedX = Math.floor(this.winw * (0.5)); //图片切换所需x位移量
        this.cssprefix = ["","webkit","Moz","ms","o"]; //css前缀
        this.imgLoadCache = new Object();  //图片加载状态储存 key=md5(img.src),value={isload:true,elem:img};
        this.scale = 1;     //默认图片放大倍数
        this.maxScale = 4;  //图片默认最大放大倍数
        this.maxOverScale = 6;  //图片放大倍数最大可达到
        // this.minScale = 1; //图片最小可放大倍数
        this.openTime = 0.3;    //打开图片浏览动画时间
        this.slipTime = 0.5;    //图片切换时间
        this.maxOverWidthPercent = 0.5; //边界图片最大可拉取宽度，屏幕宽度的百分比
        this.$box = false;  //图片容器加载状态
        this.isPreview = false; //是否正在预览图片
        var $style = document.createElement('style');   //样式标签
        $style.innerText = style;   //加载样式
        $style.type = 'text/css';
        this.$container = document.createElement('div');    //加载容器
        this.$container.id = '__previewImage-container';    //容器加上id
        this.$container.style.width = this.winw + 'px';   //加上宽度
        // this.$container.style.width = '10rem';   //加上宽度
        this.$container.style.height = this.winh + 'px';  //加上高度
        // document.getElementById('share_goods').appendChild(this.$container);
        document.body.appendChild(this.$container);     //插入容器到body
        document.head.appendChild($style);              //插入样式到head
        this.timeing = 0; //点击事件发生时的时间  记录双击
        this.timedela = 0;  //双击时间差
        this.doubleTimer = null;  //双击事件定时器
        this.bind();    //绑定事件
    }
    _previewImage.prototype.start = function(obj){  //可优化 todo
        // this.winw = window.innerWidth || document.body.clientWidth;  //窗口的宽度
        // this.winh = window.innerHeight || document.body.clientHeight; //窗口的高度
        // console.log(this.winw)
        // this.originWinw = this.winw;    //存储源窗口的宽度
        // this.originWinh = this.winh;    //存储源窗口的高度
        // this.$container.style.display = 'block';
        ModalHelper.afterOpen();
        var urls = obj.urls;    //待预览的图片列表
        var current = obj.current;  //当前预览的图片地址

        this.$container.innerHTML = ''; //清空容器
        if(!urls || !$.isArray(urls) || urls.length == 0){    //参数检测
            throw new Error("urls must be a Array and the minimum length more than zero");
            return
        }
        if(!current){   //参数检测
            this.index = 0; 
            console.warn("current is empty,it will be the first value of urls!");
        }else{
            var index = urls.indexOf(current);
            if(index < 0){
                index = 0;
                console.warn("current isnot on urls,it will be the first value of urls!");
            }
            this.index = index; //当前图片序号
        }
        this.urls = urls;   //所有图片url列表
        this.maxLen = urls.length-1;  //最大图片数 0<=index<=maxLen
        this.cIndex = this.maxLen+1;  //containerIndex
        this.bIndex = this.maxLen+2;  //boxIndex
        this.imgStatusCache = new Object(); //图片信息储存
        this.render();   //渲染预览模块
    }

    _previewImage.prototype.render = function(){
        var _this = this;
        if(this.$box===false){  //加载图片容器
            var box = document.createElement('div');
            box.className += 'previewImage-box';
            this.$box = box; //更新图片容器
        }else{
            this.$box.innerHTML = '';  //已有图片容器-清空容器
        }
        var text = document.createElement('div');   //当前张数/总张数--文本标签
        this.$text = text;
        this.$text.className += 'previewImage-text';
        this.$text.innerHTML = "<span class='previewImage-text-index'>" + (this.index + 1) + "/</span>" + (this.maxLen + 1);    //当前第几张/图片总数
        this.container = this.imgStatusCache[this.cIndex] = {elem:this.$container,x:this.winw,y:0,m:0,my:0,scale:1,scalem:1}; //存储容器状态
        this.box = this.imgStatusCache[this.bIndex] = {elem:this.$box,x:0,y:0,m:0,my:0,scale:1,scalem:1};   //存储图片容器状态
        this.urls.forEach(function(v,i){    //图片
            var div = document.createElement('div');
            var hash = window.md5 ? md5(v + i) : v + i;
            var img;
            var imgCache = _this.imgLoadCache[hash];
            //缓存图片&&读取缓存图片
            if(imgCache && imgCache.isload){    //图片已加载--使用缓存
                img = imgCache.elem;
                div.className += " previewImage-nobackground";
            }else{  //图片未加载--加载图片，加入缓存
                img = new Image();
                img.className += 'previewImage-image';
                _this.imgLoadCache[hash] = {isload:false,elem:img};
                // if(i == _this.index){   //将当前需要预览的图片加载  :  加载所有图片
                    img.src = v;
                    img.onload = function(){
                        div.className += " previewImage-nobackground";
                        _this.imgLoadCache[hash].isload = true;
                    }
                // }
            }
            _this.imgStatusCache[i] = {hash:hash,x:0,m:0,y:0,my:0,scale:_this.scale,scalem:1};  //修改缓存状态
            // img.setAttribute("data-index",i);  //未使用
            div.className += ' previewImage-item';
            div.appendChild(img);
            _this.$box.appendChild(div); //将图片div加入 图片容器
        })
        
        this.$container.appendChild(this.$box);    //加载图片容器
        this.$container.appendChild(this.$text);    //加载图片张数提示
        var offsetX = -this.imageChageMoveX * this.index;  //计算显示当前图片，容器所需偏移量
        this.box.x = offsetX;   //将图片容器所需偏移量，存入状态缓存器
        this.container.x = 0;   //显示预览模块
        this.$container.style.display = "block";
        setTimeout(function(){
            _this.translateScale(_this.bIndex,0);
            _this.translateScale(_this.cIndex,_this.openTime);
            _this.isPreview = true;
        },50);
    }

    _previewImage.prototype.bind = function(){
        var $container = this.$container;
        var _this = this;
        var closePreview = function(){
            _this.closePreview.call(_this);
        }
        var touchStartFun = function(){
            _this.touchStartFun.call(_this);
        }
        var touchMoveFun = function(){
            _this.touchMoveFun.call(_this);
        }
        var touchEndFun = function(){
            _this.touchEndFun.call(_this);
        }

        // var orientationChangeFun = function(){
        //     var angle = screen.orientation.angle;
        //     var _this = this;
        //     if(angle==90||angle==180){
        //         _this.winw = _this.originWinh;
        //         _this.winh = _this.originWinw;
        //     }else{
        //         _this.winw = _this.originWinw;
        //         _this.winh = _this.originWinh;
        //     }
        //     _this.$container.style.width = _this.winw+'px';   //改变宽度
        //     _this.$container.style.height = _this.winh+'px';  //改变高度
        //     _this.imageChageMoveX = _this.marginRight+_this.winw;
        //     var offsetX = -_this.imageChageMoveX*_this.index;  //计算显示当前图片，容器所需偏移量
        //     try{
        //         _this.box.x = offsetX;   //将图片容器所需偏移量，存入状态缓存器
        //         _this.translateScale(_this.bIndex,0);
        //     }catch(e){}
        // }.bind(this);

        var reSizeFun = function(){
            var _this = this;
            _this.winw = window.innerWidth || document.body.clientWidth;  //窗口的宽度
            _this.winh = window.innerHeight || document.body.clientHeight; //窗口的高度
            _this.originWinw = _this.winw;    //存储源窗口的宽度
            _this.originWinh = _this.winh;    //存储源窗口的高度
            _this.$container.style.width = _this.winw + 'px';   //改变宽度
            _this.$container.style.height = _this.winh + 'px';  //改变高度
            _this.imageChageMoveX = _this.marginRight + _this.winw;
            var offsetX = -_this.imageChageMoveX * _this.index;  //计算显示当前图片，容器所需偏移量
            try{
                _this.box.x = offsetX;   //将图片容器所需偏移量，存入状态缓存器
                _this.translateScale(_this.bIndex,0);
            }catch(e){}
        }.bind(this);

        // window.addEventListener("orientationchange",orientationChangeFun,false);
        window.addEventListener("resize",reSizeFun,false);
        $.delegate($container,'click','.previewImage-item',closePreview);
        $.delegate($container,'touchstart','.previewImage-item',touchStartFun);
        $.delegate($container,'touchmove','.previewImage-item',touchMoveFun);
        $.delegate($container,'touchend','.previewImage-item',touchEndFun);
        $.delegate($container,'touchcancel','.previewImage-item',touchEndFun);
    }

    _previewImage.prototype.closePreview = function(){
        var _this = this;

        if(this.timedela < 200){
            clearTimeout(this.doubleTimer);
        }else{
            this.doubleTimer = setTimeout(() => {
                this.imgStatusCache[this.cIndex].x = this.winw;
                this.translateScale(this.cIndex,this.openTime);
                this.imgStatusRewrite();
                this.translateScale(this.index,this.slipTime);
                setTimeout(function(){
                    _this.$container.style.display = "none";
                },this.slipTime * 1000);
                _this.isPreview = false;
            }, 200)
        }
        ModalHelper.beforeClose();
    }

    _previewImage.prototype.touchStartFun = function(imgitem){
        this.timedela = Date.now() - this.timeing; //计算两次点击时间差
        this.timeing = Date.now();  //当前时间

        this.ts = this.getTouches();
        this.allowMove = true;  //行为标记
        this.statusX = 0; //标记X轴位移状态
        this.statusY = 0; //标记Y轴位移状态
    }

    _previewImage.prototype.touchMoveFun = function(imgitem){
        this.tm = this.getTouches();
        var tm = this.tm;
        var ts = this.ts;
        this.moveAction(ts,tm);
    }

    _previewImage.prototype.touchEndFun = function(imgitem){
        if(this.timedela < 200){
            this.te = this.ts;
        }else{
            this.te = this.getTouches();
        }
        
        var $container = this.$container;
        this.endAction(this.ts,this.te);
    }

    _previewImage.prototype.moveAction = function(ts,tm){
        if(!this.allowMove){
            return
        }
        var imgStatus = this.getIndexImage();
        var maxWidth = this.winw * 0.3 / imgStatus.scale;
        var x0_offset = tm.x0 - ts.x0;
        var y0_offset = tm.y0 - ts.y0;
        if(Math.abs(y0_offset) > 0){  //阻止Ios系统的浏览器环境上下滑动
            event.preventDefault();
        }
        var imgPositionX = imgStatus.x + x0_offset;
        var imgPositionY = imgStatus.y + y0_offset;
        var allow = this.getAllow(this.index);
        var allowX = this.allowX = allow.x;
        var allowY = this.allowY = allow.y0;
        if(x0_offset <= 0){  //边界
            this.allowX = -allowX;
        }
        if(y0_offset <= 0){   //边界
            allowY = this.allowY = allow.y1;
        }
        if(tm.length == 1){   //单手指(图片位移)
            if(imgStatus.scale > 1){ 
                //Y方向位移
                if(imgPositionY >= allow.y0){  //超过窗口上边界
                    this.statusY = 1;
                    var overY = imgPositionY - allow.y0;
                    imgStatus.my = allow.y0 - imgStatus.y + this.getSlowlyNum(overY,maxWidth);
                }else if(imgPositionY <= allow.y1){ //超过窗口下边界
                    this.statusY = 1;
                    var overY = imgPositionY - allow.y1;
                    imgStatus.my = allow.y1 - imgStatus.y + this.getSlowlyNum(overY,maxWidth); 
                }else{
                    this.statusY = 2;
                    imgStatus.my = y0_offset;
                }
                
                //X方向位移
                if(x0_offset < 0 && imgStatus.x <= -allowX){ //左滑->初始状态到达或超过右边界->图片平滑移动到达条件-切换下一张
                    this.statusX = 1;
                    this.box.m = x0_offset; //更新位移信息
                    if(this.index == this.maxLen){ //box到达右边界
                        this.box.m = this.getSlowlyNum(x0_offset);  //阻尼效果
                    }
                    this.translateScale(this.bIndex,0);
                    this.translateScale(this.index,0);
                }else if(x0_offset > 0 && imgStatus.x >= allowX){ //右滑->初始状态到达或超过左边界->图片平滑移动到达条件-切换上一张
                    this.statusX = 2;
                    this.box.m = x0_offset;
                    if(this.index == 0){ //box到达左边界
                        this.box.m = this.getSlowlyNum(x0_offset);  //阻尼效果
                    }
                    this.translateScale(this.bIndex,0);
                    this.translateScale(this.index,0);
                }else{  //初始状态未到边界->图片平滑移动到边界->阻尼移动
                    if(x0_offset==0){
                        return
                    }
                    this.statusX = 3;
                    imgStatus.m = x0_offset;
                    if(imgPositionX >= allowX){   //右滑到达左边界
                        this.statusX = 4;
                        var overX = imgPositionX - allowX;
                        imgStatus.m = allowX - imgStatus.x + this.getSlowlyNum(overX,maxWidth);
                    }
                    if(imgPositionX <= -allowX){  //左滑到达右边界
                        this.statusX = 4;
                        var overX = imgPositionX + allowX;
                        imgStatus.m = -allowX - imgStatus.x + this.getSlowlyNum(overX,maxWidth);
                    }
                    this.translateScale(this.index,0);
                }
            }else{  //scale == 1;
                if(Math.abs(y0_offset) > 5 && this.statusX != 5){  //长图片处理
                    var $img = this.getJqElem(this.index);
                    var imgBottom = $img.height - this.winh;
                    if(y0_offset > 0 && imgPositionY > 0){
                        this.statusX = 7;
                        this.allowY = 0;
                        imgStatus.my = - imgStatus.y + this.getSlowlyNum(imgPositionY,maxWidth);
                    }else if(y0_offset < 0 && imgPositionY < -imgBottom){
                        this.statusX = 7;
                        if($img.height > this.winh){
                            var overY = imgPositionY + imgBottom;
                            this.allowY = -imgBottom;
                            imgStatus.my = -imgBottom - imgStatus.y + this.getSlowlyNum(overY,maxWidth);
                        }else{
                            this.allowY = 0;
                            imgStatus.my = -imgStatus.y + this.getSlowlyNum(imgPositionY,maxWidth);
                        }
                    }else{
                        this.statusX = 6;
                        imgStatus.my = y0_offset;
                    }
                    this.translateScale(this.index,0);
                }else{
                    if(this.statusX == 6){
                        return
                    }
                    this.statusX = 5;
                    if((this.index == 0 && x0_offset > 0) || (this.index == this.maxLen && x0_offset < 0)){ //box到达左右边界
                        this.box.m = this.getSlowlyNum(x0_offset);
                    }else{
                        this.box.m = x0_offset;
                    }
                    this.translateScale(this.bIndex,0);
                }
            }
        }else{  //多手指(图片放大缩小)
            var scalem = this.getScale(ts,tm)
            var scale = scalem * imgStatus.scale;
            if(scale >= this.maxScale){  //达到最大放大倍数
                var over = scale - this.maxScale;
                scale = this.maxScale + this.getSlowlyNum(over,this.maxOverScale);
                scalem = scale / imgStatus.scale;
            }
            imgStatus.scalem = scalem;
            this.translateScale(this.index,0);
        }
    }

    _previewImage.prototype.endAction = function(ts,te){
        var imgStatus = this.getIndexImage();
        var x0_offset = te.x0 - ts.x0;
        var y0_offset = te.y0 - ts.y0;
        var time = te.time - ts.time;
        var slipTime = 0;
        this.allowMove = false; //结束所有行为
        if(ts.length == 1){      //单手指(图片位移)
            if(Math.abs(x0_offset) > 10){ //防止误触关闭看图
                event.preventDefault();
            }

            if(this.timedela < 200){ //双击放大、缩小
                imgStatus.scalem = 1;
                imgStatus.scale = imgStatus.scale == 2 ? 1 : 2;
                this.translateScale(this.index,0);
            }else{
                switch(this.statusY){
                    case 1:
                        imgStatus.y = this.allowY;
                        imgStatus.my = 0;
                        slipTime = this.slipTime;
                    break
                    case 2:
                        imgStatus.y = imgStatus.y + imgStatus.my;
                        imgStatus.my = 0;
                    break
                }

                switch(this.statusX){
                    case 1: //左滑->初始状态到达或超过右边界->图片平滑移动到达条件-切换下一图
                        if(this.index != this.maxLen && (x0_offset <= -this.imageChageNeedX || (time < 200 && x0_offset < -30))){    //下一图
                            this.changeIndex(1);
                        }else{
                            this.changeIndex(0);
                            if(slipTime != 0){
                                this.translateScale(this.index,slipTime);
                            }
                        }
                    break
                    case 2: //右滑->初始状态到达或超过左边界->图片平滑移动到达条件-切换上一图
                        if(this.index != 0 && (x0_offset >= this.imageChageNeedX || (time < 200 && x0_offset > 30))){ //上一图
                            this.changeIndex(-1);
                        }else{
                            this.changeIndex(0);
                            if(slipTime != 0){
                                this.translateScale(this.index,slipTime);
                            }
                        }
                    break
                    case 3: //scale>1,初始状态未到边界->图片平滑移动未到边界
                        imgStatus.x = imgStatus.x + imgStatus.m;
                        imgStatus.m = 0;
                        this.translateScale(this.index,slipTime);
                    break
                    case 4: //scale>1,初始状态未到边界->图片平滑移动到边界->阻尼移动
                        imgStatus.x = this.allowX;
                        imgStatus.m = 0;
                        slipTime = this.slipTime;
                        this.translateScale(this.index,slipTime);
                    break
                    case 5: //scale=1,box位移，图片切换
                        if(x0_offset >= this.imageChageNeedX || (time < 200 && x0_offset > 30)){    //上一图
                            this.changeIndex(-1);
                        }else if(x0_offset <= -this.imageChageNeedX || (time < 200 && x0_offset < -30)){ //下一图
                            this.changeIndex(1);
                        }else{
                            this.changeIndex(0);
                        }
                    break
                    case 6: //scale=1,长图片
                        imgStatus.y = imgStatus.y + imgStatus.my;
                        imgStatus.my = 0;
                    break
                    case 7: //scale=1,长图片 到边界
                        imgStatus.y = this.allowY;
                        imgStatus.my = 0;
                        this.translateScale(this.index,this.slipTime);
                    break
                }
            }
        }else{  // 放大倍数问题
            event.preventDefault();

            var scale = imgStatus.scale * imgStatus.scalem;
            var $img = this.getJqElem(this.index);
            imgStatus.scale = scale;
            var allow = this.getAllow(this.index);

            if(imgStatus.x > allow.x){
                slipTime = this.slipTime; 
                imgStatus.x = allow.x;
            }else if(imgStatus.x < -allow.x){
                slipTime = this.slipTime;
                imgStatus.x = -allow.x;
            }

            if(imgStatus.y > allow.y0){
                slipTime = this.slipTime; 
                imgStatus.y = allow.y0;
            }else if(imgStatus.y < allow.y1){
                slipTime = this.slipTime; 
                imgStatus.y = allow.y1;
            }

            if($img.height * imgStatus.scale <= this.winh){
                imgStatus.y = 0;
            }

            if($img.width * imgStatus.scale <= this.winw){
                imgStatus.x = 0;
            }

            imgStatus.scalem = 1;
            if(scale > this.maxScale){     //倍数大于最大限制倍数
                imgStatus.scale = this.maxScale;
                slipTime = this.slipTime;
            }else if(scale < 1){//倍数小于1
                this.imgStatusRewrite();
                slipTime = this.slipTime;
            }
            if(slipTime!=0){
                this.changeIndex(0);
                this.translateScale(this.index,slipTime);
            }
        }
    };

    _previewImage.prototype.getAllow = function(index){
        var $img = this.getJqElem(index);
        var imgStatus = this.getIndexImage(index);
        var allowX = Math.floor(($img.width*imgStatus.scale - this.winw) / (2 * imgStatus.scale));
        var allowY0,allowY1;
        if($img.height*imgStatus.scale <= this.winh){
            allowY0 = 0;
            allowY1 = 0;
        }else if($img.height <= this.winh){
            allowY0 = Math.floor(($img.height * imgStatus.scale - this.winh)/(2 * imgStatus.scale));
            allowY1 = -allowY0;
        }else{
            allowY0 = Math.floor($img.height * (imgStatus.scale - 1) / (2 * imgStatus.scale));
            allowY1 = -Math.floor(($img.height * (imgStatus.scale + 1) - 2 * this.winh) / (2 * imgStatus.scale));
        }
        return {
            x:allowX,
            y0:allowY0,
            y1:allowY1,
        };
    };

    _previewImage.prototype.getSlowlyNum = function(x,maxOver){
        var maxOver = maxOver||this.winw*this.maxOverWidthPercent;
        if(x < 0){
            x = -x;
            return -(1 - (x / (maxOver + x))) * x;
        }else{
            return (1 - (x / (maxOver + x))) * x;
        }
    };

    _previewImage.prototype.getScale = function(ts,tm){
        var fingerRangeS = Math.sqrt(Math.pow((ts.x1 - ts.x0),2) + Math.pow((ts.y1 - ts.y0),2)); //两手指的初始距离
        var fingerRangeM = Math.sqrt(Math.pow((tm.x1 - tm.x0),2) + Math.pow((tm.y1 - tm.y0),2)); //两手指移动过程中的距离
        var range = fingerRangeM / fingerRangeS;
        return range;
    };

    _previewImage.prototype.imgStatusRewrite = function(index){
        var index = index === undefined ? this.index : index;
        var imgStatus = this.imgStatusCache[index];
        imgStatus.x = 0;
        imgStatus.y = 0;
        imgStatus.m = 0;
        imgStatus.my = 0;
        imgStatus.scale = 1;
        imgStatus.scalem = 1;
        if(index!=this.index){
            this.translateScale(index,this.slipTime);
        }
    }

    _previewImage.prototype.changeIndex = function(x){
        var imgStatus = this.getIndexImage();
        var oldIndex = this.index;
        var _this = this;
        if(this.index == 0 && x == -1){
            this.index = this.index;
        }else if(this.index == this.maxLen && x == 1){
            this.index = this.index;
        }else{
            this.index += x;
            this.$text.innerHTML = "<span class='previewImage-text-index'>"+(this.index+1)+"/</span>"+(this.maxLen+1);    //当前第几张/图片总数
            var hash = this.imgStatusCache[this.index].hash;
            var imgCache = this.imgLoadCache[hash];
            if(!imgCache.isload){    //图片未缓存则加载图片
                imgCache.elem.src = this.urls[this.index];
                imgCache.elem.onload = function(){
                    imgCache.elem.parentNode.className += " previewImage-nobackground";
                    imgCache.isload = true;
                }
            }else{
                imgCache.elem.parentNode.className += " previewImage-nobackground";
            }
        }
        this.box.x = -this.imageChageMoveX * this.index;
        this.box.m = 0;
        if(oldIndex != this.index){
            this.imgStatusRewrite(oldIndex);
        }
        this.translateScale(this.bIndex,this.slipTime);
    }

    _previewImage.prototype.getIndexImage = function(index){
        var index = index == undefined ? this.index : index;
        return  this.imgStatusCache[this.index];
    }

    _previewImage.prototype.translateScale = function (index,duration){
        var imgStatus = this.imgStatusCache[index];
        $elem = this.getJqElem(index);
        var scale = imgStatus.scale * imgStatus.scalem;
        if(scale == 1 && this.timedela < 200){  //双击缩小
            var offsetX = 0;
            var offsetY = 0;
        }else{
            var offsetX = imgStatus.x + imgStatus.m;
            var offsetY = imgStatus.y + imgStatus.my;
        }
        var tran_3d = 'scale3d(' + scale + ',' + scale + ',1) ' + ' translate3d(' + offsetX + 'px,' + offsetY + 'px,0px)';
        // var tran_2d='scale('+scale+','+scale+') '+' translate(' + offsetX + 'px,' + offsetY +'px)';
        var transition = 'transform ' + duration + 's ease-out';
        this.addCssPrefix($elem,'transition',transition);
        this.addCssPrefix($elem,'transform',tran_3d);
    }

    _previewImage.prototype.getJqElem = function(index){
        var $elem;
        var index = index == undefined ? this.index : index;
        if(index <= this.maxLen){
            var hash = this.imgStatusCache[index].hash;
            var img = this.imgLoadCache[hash].elem;
            $elem = img;
        }else{
            var elem = this.imgStatusCache[index].elem;
            $elem = elem;
        }

        return $elem
    }
    /**
     * [addCssPrefix 增加css前缀]
     * @param {[elem]} elem  [element]
     * @param {[string]} prop  [css attribute]
     * @param {[string]} value [css value]
     */
    _previewImage.prototype.addCssPrefix = function(elem,prop,value){    //可以优化todo
        for(var i in this.cssprefix){
            var cssprefix = this.cssprefix[i];
            if(cssprefix === ""){
                prop = prop.toLowerCase();
            }else{
                var len = prop.length;
                prop = prop.substr(0,1).toUpperCase() + prop.substr(1,len).toLowerCase()
            }
            if(document.body.style[prop] !== undefined){
                elem.style[prop] = value;
                return 
            }
        }
    }

    _previewImage.prototype.getTouches = function(e){
        var touches = event.touches.length > 0 ? event.touches : event.changedTouches;
        var obj = {
                touches: touches,
                length: touches.length
            };
            obj.x0 = touches[0].pageX
            obj.y0 = touches[0].pageY;
            obj.time = new Date().getTime();
        if(touches.length >= 2){
            obj.x1 = touches[0].pageX
            obj.y1 = touches[1].pageY
        }
        return obj;
    }
    window.previewImage = new _previewImage();
    // AMD loader
    if ( typeof define === "function" && define.amd ) {
        define([], function() {
            return previewImage;
        } );
    }

    return previewImage;
}));